Loss of CD4 T-cell–dependent tolerance to proteins with modified amino acids

In this paper, unnatural amino acids were used to probe the immune response in mice. Mouse proteins containing unnatural amino acids were injected into mice, causing an immune response to both the modified and native proteins. It was found that CD4 T cells only recognized the mutated protein, but generated antibodies which were able to target both native and mutant proteins. Since the unnatural amino acids used in this study are similar to post-translational modifications induced under conditions of stress, the authors reasoned that the same immune response may occur in those circumstances.